Hello. I'm in the middle of a PCB project and we have finished the design, but our chosen manufacturer asks for the gerber files with the extensions GBL,GBO,GBS,GKO,GTL,GTO,GTS. From what I understand, these files designate the different layers, as in .GBL is the Gerber Bottom Layer. Our manufacturer cannot use the gerber files that Ultiboard exports due to all of them having the .gbr extension. So I'm wondering if the layer files produced would be the same and can I just change the corresponding file extensions? For example, is the Silkscreen Bottom.gbr file that Ultiboard exports the same as a .GBS (Gerber Bottom Silkscreen) file?